The present invention generally relates to a storage system, and in particular relates to a virtual storage system.
Known is a virtual storage system that connects a plurality of storage subsystems and causes the host computer to recognize such plurality of storage systems logically as one storage subsystem. According to this virtual storage system, there is an advantage in that a user is able to integrate and manage a plurality of storage subsystems, and operate such plurality of storage subsystems as a single storage subsystem. This virtual storage system is also referred to as a grid storage system.
A virtual storage system is described in Japanese Patent Laid-Open Publication No. 2003-280824, Japanese Patent Laid-Open Publication No. 2005-165702, and Japanese Patent Laid-Open Publication No. 2007-213466, respectively.